SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34879d539572055792408aad0601b42afe8ade9b4e2fbf2317aec24557455578' 
  AND token = 'QqCf1OQJ2Ur7GdMhVng7FRRUbvEcXdXSABaP+1VPzIY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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