SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0d8ae449753f20b9e3f3d752a93cc642ce522950ab91d1475ccd5059de0b6b2' 
  AND token = '16DnKbfh1VCii3HnoUgPHdlqOikOaWH1BQOCvp12kjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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