SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78a30049b15251909bba2b2167c1b6136ccd25fc56cdf034f885d0fafff2d4dc' 
  AND token = 'nBlNjVNjVfFFjWo7fLYAY5yeTu9JItJ5bvTf6HJeZxA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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