SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b57256d30e32162c16abe1eaf5014762c4d4d34e062df998de64cad33cf9ecc7' 
  AND token = 'E+D0vTpp3khuryNZ7fULfpqtbCuocnNaQGViArV/vtM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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