SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a175f16595ca04ced547985938cfb917b64733b0c92deeb9beae5e59f8e2381' 
  AND token = 'apSxradAzcBsBjV+dnJRkCallYv2ejzPRyYKglVR+HA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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