SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cebf451b83b593090e95bce947c55b134f523f0a1b06ee6cd22b68632d803ac' 
  AND token = 'bd6bRhI19LqTR7CamzcDMzDKn2AKsKXFoN8DWRJnWnk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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