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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8df9467e3f8fcca1bec91d5535ca1a7571100a977d0bddc9f8e47eb6ba1cae5' 
  AND token = 'ufXCdHxK+5wF6wFMEU13sYd6sPf8dcSbKqsXMOPHqqI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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