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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8684ee34d98434c33322f7cd4ec6c4e1dd258d394a638f4840be6f14a5de4a0' 
  AND token = '5CbOQKTfSNLlEncCp29FYZLtDEVcUBcP9aqDyViGBJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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