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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ce2f3163bdeabd4fac871e4b9e05df06c51b5c5ede1fd4ec7d103bfc3701166a' 
  AND token = 'i8f9U9FLVapiPzWlcyzfAPEbJbmUIo6G2lRICsrJMoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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