SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b27b0faed2a746cf50298a3817a1dd5fb7d61c48b0831b92ccd15fffd3b4873' 
  AND token = '1EGMbgmVqfW/bN9kk5Fh4eUvOBtoJAguaEJ+ScuSjw0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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