SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc5a41eacb9e22f5f6845da46b266c3c973befa3b905f117e799a4aead37d591' 
  AND token = 'RWdBQEhDq37aFnggDj1apjvzDxNFMTRIwI5jarERNkQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}