SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90e6a55f6520290aab8b011c18ca9a0d35061c947516c284449853ba7cf2732b' 
  AND token = 'QawakolpOGHhtSPyl63eOyRLRGkwPfaSCy/hf2UBkKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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