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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfc7d5b9f06432e893ade9ef04642ac771eee9f6e64bb1ef4e23d2ee115a91d6' 
  AND token = 'b1/STIouplkQWdaHql32NxZ880Jwro1dxlQz3DpUJ4Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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