SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2eba68dc9037b4c833c73f31a7fd760df062c5b3aefa0f824ef6f840eb0074b' 
  AND token = 'gOBecikor+qGWRpja1gi1EZvKuyvbJVCi6nYn/Ultmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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