SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6829d18f9a90da82f91092f0a91ebd484be192300397ab4d612b3021bd026fdc' 
  AND token = 'kzOM3DytB+dxR8c+Ao+mzHx4vevAnmMYMO3XGKO6Vxo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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