SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f553aa7440f024460471ea06f0ec8caf75c9b9a2e34f6003e82642a3f086f08' 
  AND token = 'MsFJuTIh3DbVWul0GY+DgJwdAvN0HX0uEeHcSdtHV0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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