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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '704df67652d08e6bcd80c31383146e00c3e351ebbe36b0460e2558326aa32442' 
  AND token = '9Qs488pTNkTYA/d3Rb05XAxY6c/6CUWRdx9w0TfW2Ao=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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