SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '915596afcba415c6e1921e8801e934ce5a267b6be717a72409a1eac244905f0e' 
  AND token = '0hvcrTxarMrxLx4SoCAQlak57LGhRTuQsRy1hrF9yCc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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