SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '548df5a0571829a0393b289841f3ddb91df3f3c051a4cecc5edcf6d15af0a913' 
  AND token = 'CfjwqY7ymtuzueUTArwDLJ+8JMggzn/sBXsf2SAmkkk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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