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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a0d3c25f31733dcce71bccc7ae4115c32cfe124e65c3df38c4f76667f61cbf00' 
  AND token = '53cwTIr0p96TVEd/oLblrXdkk+dCDB8vxZcVSj4UxCk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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