SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ed8e8a53ad8e77699a6daade6bf5dd81c8cbafc390e180360fd5831cd127ab7' 
  AND token = 'Z1fHL2hPmPdCIdwnErxkDLCx1V6xUzsEFyMmWVB9C/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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