SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9131cb673ac4165203a82a05b506b2015f828d3c897dae43cb400e318e94345' 
  AND token = 'Ajp3FslTGK+oY1F53wGbQgeEbvMAOzSQax+odblWH88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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