SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8e5fa75f43f0e2381b8258787630c834b452c1c612c94dd8638a40b8c9176b61' 
  AND token = 'UwnsgFTv/nRm6PHW+x7ZBZq5lJvbUg3ffZPY4exc8dY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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