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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b37240e5d8666d807cd29495e6cc07c22ff9e63a84c5bc39237dbcf775e54cc3' 
  AND token = 'WzDg7V9JeSau9MKnT+Ej5RkwaWc5nB02dbT+JNip75k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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