SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b0274a5dc48ed63b48dbff5db858a4fae8183df245db6e9d2299b2c75807314' 
  AND token = 'xAt93BDVbeGTgAy5Uees3N6vYz/ZSxBeC+egHgrdlhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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