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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b122d16fdc041b5679d1d7e246243eb2e8d2eba897d0ccfdbd6d53b6de055ed2' 
  AND token = 'yXY/MQSK5ds9wbOnl+DZmLG1ABwvkMvjOcjNuy5Ptu0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}