SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fca472fcbf4e2899190912d7b885b95a7193b39dd636cac7f6a2f3ada80dace3' 
  AND token = 'U5hLgrmbPsG2JXQ30Fmh3+/AYXYjN3wlfSZOSaD6Uks=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}