SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f23ef0ac426e2baa285c5eb5a47a7fc75bc8038a8f5b85865701e57737a161c' 
  AND token = 'XQgZmAxLrW1eGbAjQXVv2RyIJ3iPzK/iTaUxs+jtlL8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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