SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d54b0fb44d8a611639750ab54bac83d9147597de12c055e2044aafeefcbc5df' 
  AND token = 'WUNl54D9gIgOB4vAZ+3PoVHL2ReLsRC/RDEXbWKZwjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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