SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '507a1e5b58f51dfee35797c72550a0ffc033409341a88b4085eb179693faeea1' 
  AND token = 'LmSQbVCdVbVJFaBZcXsNW/PDRyB2Eij3r2GngvNJEw8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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