SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffc7bd8166748ea7d5a4fc2603d7d623184f13689b306d060122cc45b7da71ff' 
  AND token = 'QetSUOVQm3evRBm+nL8X0sg+ugSdyG4nW9x5fY3vU2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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