SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f768df691485b0953dee02fcff8f2e5e760404baa6853721552aa5a5e3c74e8d' 
  AND token = 'mYDnpfOY+pZioCO4pXSgj16wEwZl2vAukNUMv7lVV3Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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