SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '518311561c3e64d6939ba7e3e9ab094deed2b7080063ba5ce305826c2486d116' 
  AND token = 'R6FJVmESWokS/kyUWj1KOfCbUHhk2iaNVUMzi/aYhJs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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