SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8b94a3bcac9aa6f88299a2f4cc57396476ce51fd57aa2a5f2b0ed4ffbf9bd56' 
  AND token = '91lbCwuo/gujlmGIcVjN5XVHdsQVDm+1JaTvgAALbh4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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