SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8a88d189238e445f2986aee871c8c56874ea6212e8fdf78c854d350d629e5bf' 
  AND token = 'ldnKT5k51gGVQUynmcnStgAWVkTtYMiIb/zmy0Qy/8I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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