SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b54e7781201800a4f580c8a95c86d4ff168a1063ee2c05640179703c91d6488' 
  AND token = 'XEMOx0hHPIbv+TK8Ozv859F87NXw4inBMqwZSay0swg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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