SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd68a6c0936475172ddede8ac9c7946289d09c0b02e1873d6176af0e704f820f8' 
  AND token = '0JUporemI6yhkCdzyxL1ubnNhnOyrklUIb+0ZMhP0ck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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