SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a94eb06921e989004a2b2a66fac8457ff522adad4e11211dc3c149ba3aea15c' 
  AND token = 'qKhe3ybZDxUPGZbrM/Cx8aXFqLcxA+8OmqtJhwSXIjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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