SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42ce22c5493ce98344fa6d68c98575898006241a811c2679163f5e49e766b8b9' 
  AND token = '7U8JGv6wVzgcCi2PnR07Wm/YywUYeJ3x+staZGkHBVI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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