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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fed75dd75b911184d9921e7042cecdfe9c10edbe2211af81adf8dbcc40de5e87' 
  AND token = 'hKVe8TTyGO8aUKgRhoWYJMebXfzbS4WEb3Im2Zj2tVs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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