SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a24b3f1d761f6dcb429efe7ea6b20ab183fee22e2924b47fd8c2731d8df30ec' 
  AND token = '6mrgITGGlBiIENoh+PfzP7PiYxxALV4XLDKa3PQ+PK8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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