SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1466e2dc3ed80bd644dbd207fbfae1e0b61c5b575fc0c16144c999061c1eb0fb' 
  AND token = 'IY+3VYjcNRSdiaJ7bfMnU54sbUCwLicDjPMcnB7/JA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}