SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54867a678991ec3b2bce4019006dbc12d232d52699e901d815d803d55465bfaf' 
  AND token = 'oiAasTdvKg++EyrYrq98SrryAWFUqpT/ius2AoMiMUw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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