SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b798e5f5489a20abaa04c1252107097dcde6a58fa0d5a1aa79d5c9a56cfc0653' 
  AND token = 'gPdkxyzHjEGex6wWsM+YceEfubXLXY1MkdYY9jXbzrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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