SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'beb4d7eb4f4c5bc91103170418ad957f15aa4eaf41b222149c1a323c707d0b68' 
  AND token = 'fQ2kjJWvsk0ZxXhKWBltpNgGZTvAz8n6ZL2Qll4+wCM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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