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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14fcd4b3c7f33d70fe75a3e8ee3d2fd5b902f17e1ec9f8aaa529ef3904de698c' 
  AND token = 'ubyDTvLtl88q2JKQEjTvj51tumyffnVijHaRWSsyZkQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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