SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ac81169037613b16884ece9c4120954234b652009c6f80c91bf518293ca45f1b' 
  AND token = 'FLYl7oV/zjX+r77Ca6h7s6o8KZXAX1RdUjcJjR7CIfk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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