SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd55f9bd9e692c17f335656335ed3475cfc6851291acade04fbefc6055ddbf237' 
  AND token = '6gywpBbAKIlpHUEjLVDauYwtM7LLMcizJKw8ylCC/7s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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