SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b7b524738ea38034a0fe7f4499606e1ac68e3a444b27d22d71254d980314a2b' 
  AND token = 'j0RVUPgXfbbDmhbRNa34Sf3EhteCbEzY38e0riOlPmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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