SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fdb38b8893eb3f5808bb694c326957d8ac30f6934bdbe2210ffc68e890b1f0b' 
  AND token = '3mFL34J0lbvZwXhG5/HS5qqKR5RxPJZFA7xlpDYPsww=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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