SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8645a7ad7111758f5c99e50cb03a3c9cd4cebf8b55cbef2e3a31efc0b02b6182' 
  AND token = 'CgLl6HABo+ciz3WJJc+MsuXLx4HUjJszRJPZLd3AbTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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