SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2b7d2779f9083913b3b174fb1fb0218d52c43b510cc853d0b29ece35bc608c1' 
  AND token = 'v6gASKYGrI2Um+89/Ru4WHeTAsgBwIr1sHzeiOA9YVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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