SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51fd39ebea6597c3d2295094594dd3a6b8ae1a8fef03171fc99a56df0cf75b7d' 
  AND token = 'zdiu5j5PdPst/kkRAFHERtKKgh9+DctMnbGXSNWgSRs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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