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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3f2006d39138ebb317e0ddcda70e370db9b93136f54bbee0d88b458bd285bb6' 
  AND token = 'yVI2+gZ8v2wZC9QN9cjDQzXmolv5hIYIDMtLsHyjv3k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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