SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1da68f1c87fc024288d0cef94694ba8bff360ee92eef775c70be1f70e574a174' 
  AND token = 'oStVIR+52R1qwaXl+SpFIB++RKoC0TqAPzfOqvEgZi0=' 
  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"
    }
  }
}