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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c99b35a7c7bb32cbebb296e946e28333009ff52f529b0c2f9f2f92c701f5ff4f' 
  AND token = 'LjUnv/Sev8p/pQQjF0LSt9TP2lLxHaXwGLKQlWG2Pt4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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