SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97fd76fdb668e77bbb65579b7b266c4eb31712cd8fb79179d11ea789274c83dc' 
  AND token = '/BUS/YLEIGwNzAkpmbUSHQbhC1xRf/lgLtchi2ZsoV8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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