SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a541ca28e8ea8a3948ba80d52211d6643fa832e3dca7b3ee91c23abc172c4c54' 
  AND token = 'ut9pWXOM0eL1PuHEVlLHl/v61Vrdiy+sLFwx09JSzQk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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