SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88590a78d137718bea5b0de06ababed254799c34a0a74865a512ecb917fe9f2c' 
  AND token = 'nf6V0UGdjCXaZHXtV9Uy/jMhQfxvJJFfXG+4pdrVwAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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