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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8d8bd1dc5b596a11542c556cf78fe5137f80f6a11b0029a6311367f0eb7e907' 
  AND token = 'JLaTOHmqAj1Yjls2qMZDOKJW1fB7kXTBdXtMc2pBZis=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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