SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6dbd86306ea0b57d3b2a863b8b32618f8435124731967900b7e606ce0dd6e0e' 
  AND token = 'VeV8CUZuZr+wDU6YPcjLjYavIFmEVBu7zKjiT+9UQJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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