SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bbe39220d00e8ba733eac91c5aa766f5c0021933fa966b9617af39844dda2f38' 
  AND token = 'cLE1WvvKjj0auAPygidXXVEEPAY7oR2nCAHuuGx4/YY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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