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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'be69a3ce8829b43fa2d593eb46fed455930f670aa0e6a4fb45cdf4ceb8974e81' 
  AND token = 'k3IxBXHd6fBuASSTg+Z71Vd3fd+AGDQueg7QVEXomKc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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