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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd09373171d9098ce9e4ed7bbcd46a9f7cf993add5ad1b3a53d3e3a5bc86db710' 
  AND token = 'sUCEuUHH18I9kzoN4khNCaKHIgJJ/KM2z8h0DVUfjJs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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