SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82b5137e237bc442192abe93bee83f5cfddfcf48dad7f100341ef011dadd14bc' 
  AND token = '2Ssyad7PRRyQvINr88IcsTyekqpy0MA1rMgZrqymnTA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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