SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '783c15c67720b097d97159d226e45b285cf043a6a05617a72ab4721fa6889832' 
  AND token = 'kf4zwgKSv0B2Xdpq5yxP5wLADWYlw+dDI09LyWvW2Og=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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