SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c3cfd9de5ac3a42d44c16c9aeecc7a4d0fab6b6ea8cb1cf0ef9118866103552' 
  AND token = 'G9FEOgu9iXL2nZdcwgxmqY9PwhKL7+TBWbvZPnuLRPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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