SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a42ec47bc5b78870556d844b8366c33a451576181e642d08a6f4cb45863e578' 
  AND token = 'PUEaEAGdfc6vPeWkpqu/L0yKJOTEYT16z0c1N2qfy9A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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