SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be77993ec15b6d967541b2a4c7cd314666db2c2f19b86bd3f38bd97578c15c96' 
  AND token = 'ux5x3uAcnayNwojVxx+AJCi8JpmZb/BW+iLLJM+BH3g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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