SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '847aa3d35e6064983f49df5eabb128fff8b1bb06f49da01ca7d855c168bd496f' 
  AND token = '1ECZKSbqqPSIJxtRQMwTEcAHCQF5IOPAQ4fEbb++gFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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