SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f33870386f3549763a9d6cde7979afbb30c261dfe8dc3849f94d64fe6453c358' 
  AND token = 'NYeE1PZyJVw7i2oXMqIaavmbFJ+EWsKubuVutA9U8vg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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