SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a23ef10c640491f44af2f313cda4d111959c59cf2d9ec12816e9bbccb12b3800' 
  AND token = 'n+cuRvHWYsaX2cneXXOxcSxY4GZ8CBgLI8oD5zskzIk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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