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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b48d2654e40634eaedd90f08c46e8ccdb1e31f88019c70dec962268493450fc' 
  AND token = '56yov+STeyeaam32piQOUYVHRGMMqEVaJpzjkOMbTkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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