SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '417c9b0ef97d4422a0369bf7e5ef20e3b2e4cebae8b4969be900699d51acf6c1' 
  AND token = 'S6zuQH9/DRIAF9ySjfXqnU6zPHZdesJ37GOSd+rm/fs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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