SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7abfe4eee8968b32f27278a486f4c795203b1388e992b4d1d540b27382b0166c' 
  AND token = 'PXHIxhykLdMM2Tx/ESYNyWbzd0O5LEcRD7daUqMf8G0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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