SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4dc81198d571adffdb9614e4d90e8bf9f6eb12d16431adc3898afdbf6d553cb' 
  AND token = 'S7KBIXvIFbEdJ9L+nAyiwlxsZ9MatqHGXevA1RIm4DA=' 
  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"
    }
  }
}