SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '535ccd791a734054f4cc3104c3ad58e4834dec5eb509f741dda533fdbd8364f7' 
  AND token = 'rGZMh7+UghQmLCH96mKgB4O3p/zKd0mSkJUvBIQISUE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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